Snowplow Route Optimization for SDDOT

The South Dakota Department of Transportation (SDDOT) is responsible for operating nearly 7800 miles (8450 lane-miles) of highway. The state network is predominantly rural two-lane highway, but also includes rural and urban Interstate highways and 4-lane rural expressways. Winter maintenance—comprising snowplowing, anti-icing, and deicing activities—is performed by 25 maintenance reporting units operating from 71 maintenance shops and 11 remote stockpile locations. SDDOT’s equipment fleet includes 428 tandem-axle trucks equipped with a variety of front-, side-, and underbody-mounted plows as well as 21 tow plows. Staffing levels permit SDDOT to operate a single extended-hours shift statewide, with limited overnight shifts on Interstate highways near Rapid City, Sioux Falls, and Sioux City, Iowa. SDDOT faces several challenges meeting road users’ rising expectations for winter level of service, including constrained budgets and staffing levels; rising costs of equipment, fuel, and deicing materials; and staffing availability in rural areas. To help meet these challenges, SDDOT has established performance measures related to resource utilization. SDDOT is also examining new ways to define level of service, which is currently defined in terms of plowing frequency during winter storms and clearance time after storms on two classes (priority and non-priority) of highway segments. SDDOT has also begun expanding its Maintenance Decision Support System—which uses weather forecasting, real-time feedback on location and treatment activity from snowplows, and computer modeling to predict future surface condition and to recommend cost-effective maintenance treatment types, rates, and timing—from approximately one-third of the state to the entire state. To further improve its winter maintenance effectiveness, SDDOT wants to consider whether other potential changes—such as snowplow routing, location of remote stockpiles, staffing levels, equipment type and allocation, and others—are technically feasible, economically advantageous, and beneficial to road users. The objectives of this project are to: (1) Create and calibrate a snowplow routing model that can accurately represent SDDOT’s current winter maintenance operation and reliably evaluate alternative routing strategies; and (2) Use the calibrated routing model to identify more efficient and effective winter maintenance strategies.